title: Monitoring phospholipids for assessment of ion enhancement and ion suppression in ESI and APCI LC/MS/MS for chlorpheniramine in human plasma and the importance of multiple source matrix effect evaluations.
abstract: Biological matrix effects are a source of significant errors in both electrospray (ESI) and atmospheric pressure chemical ionization (APCI) LC/MS. Glycerophosphocholines (GPChos) and 2-lyso-glycerophosphocholines (2-lyso GPChos) are known to fragment to form ions at m/z 184 and m/z 104, respectively. Phospholipids were used as markers to evaluate matrix effects resulting in both ion suppression and enhancement using ESI and APCI modes in the determination of chlorpheniramine in human plasma. Results revealed that GPChos and 2-lyso GPChos demonstrated very low ionization efficiency in the APCI mode, post-column infusion experiments were performed to confirm that suppression and enhancement matrix ionization effects coincided with the elution profiles of the phospholipids. The mean matrix effect for chlorpheniramine using APCI was 75% less than the mean matrix effect in ESI, making APCI the ionization method of choice initially even though the absolute response was lower than in the ESI mode. The resulting APCI method showed acceptable results according to the FDA guidelines; however, a multiple source relative matrix effects study demonstrated variability. It was concluded that an absolute matrix effects study in one source of biological fluid may be not sufficient to ensure the validity of the method in various sources of matrix. In order to obviate the multiple matrix source variability, we employed an isotopically labeled internal standard for quantification of chlorpheniramine in the ESI mode. An additional validation was completed with the use of chlorpheniramine-d(6) as the internal standard. This method met all acceptance criteria according to the FDA guidelines, and the relative matrix affects study was successful.
authors.affiliation: Virginia Commonwealth University School of Pharmacy Department of Pharmaceutics, PO Box 980533, 410 N 12th Street, Richmond, VA 23298-0533, United States. oismaiel@vcu.edu
authors.forename: Omnia A
authors.initials: OA
authors.lastname: Ismaiel
authors.forename: Matthew S
authors.initials: MS
authors.lastname: Halquist
authors.forename: Magda Y
authors.initials: MY
authors.lastname: Elmamly
authors.forename: Abdalla
authors.initials: A
authors.lastname: Shalaby
authors.forename: H
authors.initials: H
authors.lastname: Thomas Karnes
mesh_terms: D002744:Chlorpheniramine / Q000097:blood*; D002853:Chromatography, Liquid / Q000379:methods; D004155:Diphenhydramine / Q000032:analysis; D005997:Glycerylphosphorylcholine / Q000032:analysis* / Q000737:chemistry; D006634:Histamine H1 Antagonists / Q000097:blood; D006801:Humans; D008246:Lysophospholipids / Q000032:analysis* / Q000737:chemistry; D012015:Reference Standards; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D021241:Spectrometry, Mass, Electrospray Ionization / Q000295:instrumentation / Q000379:methods; D053719:Tandem Mass Spectrometry / Q000295:instrumentation / Q000379:methods
chemical_list: D006634:Histamine H1 Antagonists; D008246:Lysophospholipids; D002744:Chlorpheniramine; D005997:Glycerylphosphorylcholine; D004155:Diphenhydramine